Patent GB-1411045-A (GB)
Title: Pipeline end closure
IPC: F16L1/14
Filed: 1973-09-17
Abstract: 1411045 Pipe stoppers HYDROTECH INTERNATIONAL Inc 17 Sept 1973 [20 Sept 1972] 43563/73 Heading F2P  A pipe stopper to be mounted on or in a pipe end for use undersea comprises a housing having grippers to engage the pipe and connect the pipe and housing, seals to prevent fluid flow from the pipe, and a pressure fluid servo actuated to disengage the grippers from the pipe. In one form, a pipe stopper housing 20, Fig. 2, is inserted into the end of a pipe 22. Liquid under pressure is admitted through a pipe 58 to cause a ring-shaped piston 52 to move leftwards. A flange 51 around the piston slides a series of segments 26 leftwards, together with a sleeve 27, sealing rings 33, and a second sleeve 34, to engage a lug 40 on the stopper housing. As the piston 52 continues to move leftwards, the segments 26 are cammed radially outwards up frusto-conical surfaces on the sleeve 27, into friction engagement with the inside of the pipe 22, so that they wedge firmly. The segments 26 have teeth on their outer faces, to increase their grip in the pipe 22. As liquid under pressure continues to flow through the pipe 59, the whole housing 20, &c. moves rightwards. The lugs 40 on the housing slide the sleeve 34 rightwards, to compress the sealing rings 33 and expand them radially to engage the pipe 22, and a second series of segments 25 are cammed radially outwards by a frusto-conical surface on the sleeve 34 also to grip the inside of the pipe 22. The stopper 20, &c. is now locked in the pipe 22, without continued application of liquid pressure through the pipe 58. A seal 53 is expanded radially to engage the pipe by applying liquid pressure through a duct 54. The sealed pipe 22 can then be lowered to the sea bed with a cable attached to a lug 23. To evacuate water, &c. from the pipe 22, a valve 47 admits pressure through a pipe 46 to a pipe-line pig 45. With the pipe 22 thus lightened, it can be raised from the sea bed. To remove the stopper 20 from the pipe, the pressure acting on the seal 53 is reduced, and liquid under pressure admitted through a pipe 59 to the left hand side of the ring-shaped piston 52. The piston flange 51 then engages the segments 26, and the whole stopper housing 20, &c. moves leftwards, unseating the second series of segments 25, allowing the seals 33 to contract radially, and releasing the series of segments 26. In another form, liquid under pressure admitted through a pipe 72, Fig. 5, slides a ring- shaped piston 69 leftwards, which in turn similarly slides leftwards a split sleeve 77, sealing rings 78, a pressure test ring 79, and further seal rings 80. The seal rings 78, 80 are thus radially expanded to engage the inner surface of a pipe 61. At the same time, springs 89 between a flange 70 on the piston 69 and a series of segments 85 force the segments up cam surfaces on the sleeve 77 to wedge between the stopper and the pipe 61. Pressure is then applied through a pipe 83 to the pressure test ring 79 to see if the seal rings 78, 80 have seated properly. To remove the stopper from the pipe, liquid under pressure is instead admitted through a pipe 75, to slide the ring-shaped piston 69, &c. rightwards. A second series of segments (96) Fig. 7 (not shown), may wedge between the seal rings 80 and the radial wall 62 of the stopper. In a further form in which a stopper housing 101, Fig. 8, surrounds a pipe 100. liquid under pressure is admitted through a pipe 117 to a ring-shaped piston 111 which slides leftwards, in turn sliding a split sleeve 119 leftwards to compress seal rings 125, 127 so that they expand radially inwards to grip the outer face of the pipe. A series of segments 120 are slidden leftwards by springs 123, and are cammed inwards by tapering surfaces inside the split sleeve 119 to wedge against the pipe. Pressure is then applied through a pipe 129 to a pressure test ring 126 to ascertain if the seal rings 125, 127 have correctly seated. A pipe pig 107 can be propelled down the pipe by admitting pressure fluid through a pipe 109. To remove the stopper from the pipe, liquid under pressure is instead admitted to the piston 111 via a pipe 115, to slide the piston rightwards.